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How To Run Multiple Scenes Simultaneously using the Activate Scene Actor

Modified on: Sat, Mar 10, 2018 at 5:50 PM

Isadora’s powerful scene system includes a useful feature for operating multiple scenes simultaneously: the Activate Scene and Deactivate Scene actors.

These actors are exceptionally useful when you need a specific video or audio asset to play consistently across several scenes without interruption. It’s also a great method to facilitate unbroken communication between sensor data and generated effects (such as ArtNet communications or Kinect sensor data) as your move from one scene to the next. Finally, activating and deactivating scenes is an effective way for interactive pieces to combine complex effects and user actors on-demand without taxing your computer’s resources. Instead of building a complex patch with myriad user actors into a single scene, each component can be moved into its own scene and activated only when needed by the project.

How does it work? The Activate Scene actor allows you to activate a “secondary” scene in addition to the current “primary" scene. This secondary scene remains active until it is deactivated using a Deactivate Scene actor.

The primary scene is illuminated in the Scene List in dark blue with a green line beneath it; other active secondary scenes are illuminated in a light blue.

In the above image, “Q2: VIDEO 1” is the primary scene, and “Q1: AUDIO” and “Q4: VIDEO 3” are the active secondary scenes. “Q3: VIDEO 2” and “Q5: OUT” are not active.

Isadora does not limit how many secondary scenes you can have active at a time, but each active scene uses computer resources as normal.

You cannot activate the current primary scene, however, it is possible to deactivate it. Activating a scene that is already active does not reset the scene, nor does it activate a duplicate.

Organizing the Scene List

Scenes are either the primary scene, a secondary scene, or not active. An activated "secondary” scene which later becomes the “primary" scene won’t remain active after leaving it. The scene's status as a “secondary" activated scene disappears once it becomes the “primary” scene, and afterwards it behaves just like a normal scene.

For this reason, it’s important to ensure that your scene list is carefully organized so that the project will not accidentally transition into a scene you want to remain active. As a best practice, we recommend placing scenes you plan to activate or deactivate at the beginning of the Scene List, followed by a blackout scene and then a “pre-show” or opening state scene. When you operate your project, manually skipping past these scenes prior to the start of the performance. If you later reorder your scenes, this ensures activated scenes remain a fixed position in the Scene List so there is no chance an operator will transition into them. This also retains the scenes relative position in the scene list, as opposed to placing the Activated scenes at the end of your project, which may later require updating the individual Activate Scene actors if more scenes are later added to your project.

Therefore, planning a project using Activate Scene requires some careful thinking ahead. In this example, we’ll show you how to think about organizing your scenes while we learn how to use the Activate Scene and Deactivate Scene actors.

Try it!

Suppose we have a single piece of music we wish to play, but the video changes between several images. While we will be transitioning through several video cues, but we want the audio track to proceed unbroken. We can’t use a pre-recorded sequence because the exact timing of the video transitions needs to be manually triggered, but the music must continue separately. This is a relatively common scenario in many media-heavy works, and the Activate Scene actor is the perfect solution.

To begin, you’ll need the following media files from your own collection:

An audio file in .mp3 or .wav format.

A few pictures or movie files, at least four or more if desired.

[Optional] An image or video file with an alpha channel (such as a transparent .png)

Step-by-Step Guide

Start a new Isadora project, and import the media you selected.

We’ll use the first scene to play the audio file. Name the scene “AUDIO”.

Place a Movie Player (if you are using an .mp3 file) or a Sound Player (if you are using a .wav file) in the scene. Set this actor to play your audio file on a loop. Don’t set a fade out time for this scene.

If you are using a Sound Player, don’t forget to use an Enter Scene Trigger actor to connected to the ‘start’ trigger input to initialize playback.

Create a new scene after the first scene. Name the scene “PRESHOW”, but leave the scene otherwise empty to create a blackout cue. Set a fade out time for this scene, 2-3 seconds is appropriate.

Create another new scene. Name the scene “VIDEO 1”. Add a Movie Player or Picture Player displaying an image or movie of your choice, connected to a Projector actor for output. Set a fade out time for this scene, 2-3 seconds is appropriate.

Repeat Step 5 to create two or three more scenes, as above. Name these scenes VIDEO 2, 3, and so on. Be sure to play a different image or video in each scene!

Finally, create a scene called “OUT”. Leave this scene empty for now.

At this point, we’ve created the simplest set of Isadora cues. Your scene list should look something like this:

Double check that you can transition from one scene to the next using the space bar as normal. You should have a blackout scene with music, followed by a blackout scene, followed by a transition between a few different images, ending with a another blackout.

Next, we will use the Activate Scene actor to start the audio file playback we set up in the AUDIO scene. By placing the Activate Scene actor in the VIDEO 1 scene, the audio will continue to play unbroken as we transition across the VIDEO scenes. Finally, we’ll use the Deactivate Scene actor to fade the audio out in the scene called OUT. Here’s how to do it:

Go to the VIDEO 1 scene. Add an Activate Scene actor:

The Activate Scene actor requires us to plug in a few pieces of information to activate the right scene.

First, we need to connect some kind of input to the ‘trigger’ input. This will be the command that actually causes the scene to activate an appear. This is best done with either the Keyboard Watcher (for when you want to manually activate a scene) or even better, with the Enter Scene Trigger actor, which causes the secondary scene to activate alongside the primary scene. In this example, let’s add an Enter Scene Trigger actor, then connect its ‘trigger’ output to the ‘trigger’ input of the Activate Scene actor as shown below.

Now we need to specify which secondary scene the actor will activate when triggered. This is defined using both the ‘mode’ and ‘scene’ input properties. First, the ‘mode’ input is set to either ‘relative’ or ‘absolute’, and defines how the value in the ‘scene’ input property behaves.

When ‘mode’ set to ‘relative’, the number of the current scene is added to the value in the ‘scene’ input property to determine which scene is activated. Thus, if the value in the ‘scene’ input is ‘1’, the activate scene actor would activate the next scene in the scene list.

When ‘mode’ is set to ‘absolute’, the value of the ‘scene’ input determines which scene is activated directly, thus ‘1’ activates the first scene in the scene list, ‘2’ activates the second scene, and so on.

In this example, we know we want to activate the AUDIO scene, which is the first scene in our project. Set the ‘mode’ to ‘absolute’ and the ‘scene’ input value to ‘1’. Placing activated scenes at the start of the project makes this method handy best practice.

The ‘transition’ input determines the layering and blend mode for the new scene:

‘above’ renders the secondary scene on top of the primary scene using a transparent blend mode that will obscure the underlying primary scene as it fades in.

‘additive’ will render the new scene with an additive blend similar to the ‘additive’ mode of the projector actor.

Since we are only playing audio in the secondary scene, leave the ‘transition’ input set to ‘additive’ for now.

Finally, the ‘fade’ input property defines the fade-in time, in seconds, for the activated scene. Set this as desired, 1 to 3 seconds is best depending on the audio file you are using.

Once complete, our VIDEO 1 scene should look something like this:

Now, skip ahead to the scene we created earlier called OUT. This was an empty scene before, but now we are going to add the Deactivate Scene actor to it.

The ‘trigger’, ‘mode’, ‘scene’, and ‘fade’ properties behave identically to the Activate Scene actor, except the actor is used to deactivate a previously activated scene.

As before, add an Enter Scene Trigger actor connected to the ‘trigger’ input of the deactivate scene actor.

Set the ‘mode’ to ‘absolute’ and the ‘scene’ input to ‘1’ to correctly deactivate the AUDIO scene.

Set the ‘fade’ input property to any value you like, 3 seconds is appropriate.

Your OUT scene should now look like this:

Putting it Together

Starting at the PRESHOW scene, run through your project. You’ll notice that when you go into VIDEO 1, the AUDIO scene activates as well.

Press the space bar to transition from one scene to the next. As you do, the AUDIO scene remains active and the music continues to play, but the video images change on-demand.

Once you reach the OUT scene, the AUDIO scene fades out:

Cross-Scene Communication

An activated secondary scene is “active” in every respect. Control, communication, and mouse and keyboard actors are all fully functional in an activated scene and work normally. However, the Scene Editor only displays the primary scene, and the Control Panel only displays controls associated with the primary scene as well.

We can also communicate between two active scenes using the Broadcaster actor (to send information) and the Listener actor (to receive it). This is useful if you want to alter the actor properties in an active scene, or to use data collected in the secondary scene to power effects or manipulate actors in the primary scene.

Try it

Go back to the AUDIO scene.

Add a Listener actor to the scene. Set the ‘channel’ property to ‘1’.

NOTE: All Listener and Broadcaster actors you want to share information between must be set to the same ‘channel’. Remember to use different ‘channel’ numbers if you are working with multiple different input/ output pairings at once.

Connect the ‘value’ property of the ‘Listener’ actor to the ‘volume’ property on the Movie Player.

Now, go to the VIDEO 1 scene. Notice that the AUDIO scene is activated, and you hear the music playing.

Now, add a Broadcaster actor to the scene.

You’ll notice that immediately, the music suddenly stops. It actually hasn’t, we’ve just set the volume back down to 0 because that is the default ‘value’ for a new Broadcaster actor.

Change the ‘value’ property to 100 and you’ll hear the music again! Try a few different values from 0 to 100, and notice that you can now manipulate the volume of the AUDIO scene from the VIDEO 1 scene!

NOTE: The Broadcaster actor only transmits new data when the value is updated. If you wanted to alter the volume as we moved from scene to scene, we’d need to use a Trigger Value and Enter Scene Triggers to pass new values to the Broadcaster. You must also set the ‘initialize’ function of the ‘value’ property to a value that is not equal to the value being received from the Trigger Value actor. Simply placing a Broadcaster actor in each scene with the new values won’t pass the new values.

This will create a ‘hard cut’ in the values. Experiment using other actors, such as the Envelope Generator, to create fades or smoother transitions.

Try adding other Broadcasters in later scenes to change the volume as you move from scene to scene.

Experiment by using multiple Broadcasters and Listeners connected to other properties. Remember to use different ‘channel’ numbers if you are working with multiple different input/ output pairings at once.